Watercraft are often powered by an outboard motor positioned at a stem of the craft. The outboard motor has a powerhead and a water propulsion device, such as a propeller. The powerhead includes a cowling in which is positioned an internal combustion engine, the engine having an output shaft arranged to drive the water propulsion device.
Generally, the motor is connected to the watercraft in a manner which permits the motor to be "trimmed" up and down. For example, the motor may be connected through a horizontally extending pivot pin to a clamping bracket which attaches to the watercraft In this manner, the motor may be moved in a vertical plane about the axis of the pin. This allows an operator of the watercraft to raise the propeller out of the water of place it deep in the water dependent upon the trim angle of the motor.
In addition, the motor is arranged to turn left and right about a generally vertically extending axis. This arrangement permits the operator of the watercraft to change the propulsion direction of the motor, and thus change the direction in which the watercraft is propelled.
The size of the motor, especially the powerhead portion which includes the motor, effects the air drag associated with the watercraft. It is desirable for the motor to have a small profile to reduce the air drag. In addition, it is generally desirable for the engine to be compact, since this makes the task of trimming and turning the motor less difficult
Several problems arise when reducing the size of the engine to reduce the size of the motor. A primary problem relates to the heat generated by the engine. As stated above, the engine is positioned in a cowling, and as such the heat generated by the engine is trapped in the cowling, resulting in high temperatures within the cowling.
At the same time, in order to reduce the size of the engine, the engine components are generally placed very close to one another. Heat may be transferred between closely positioned components, damaging more heat sensitive components. This problem is especially acute in the outboard motor setting since the temperature in the cowling is already quite high.
An engine arrangement for an engine powering an outboard motor which is compact and reduces the problems associated with the transfer of heat between one or more components is desired.